Why everybody always misspell my nick?
"harmonics" is pretty common too.
Watch what you take away from my post mostanks, notice I said "these two particular fish" - I've seen quite a few large male N. brichardis and pulchers with no hint of a hump at all. Just keep that in mind when trying to judge by head shape. Actually, keep that in mind for anything at all having to do with fish keeping. Even my advice, which you thoughtfully describe as "experienced info" should not be applied blanketly. There are exeptions to every rule. (Except the rule that says fish have to have water.
)
Anyway, for more on sexing, you can make a more acurate judgement by observing their behavior rather than trying to compare body structure. Even when not in pairs, a male's normal behavior will be centered around patroling a territory, (real or assumed) while a female's will be centered around nesting. I have (or at least had) tons of pics of various brichardis/daffodils that support this. Look at the two I posted here. Notice the male is against a higher open water backdrop, while the female is against a lower rock structure backdrop. Of course they both will take breaks to chase other fish around.
(Again, this is not 100% true across the board, but it is common) So, does your daffodil spend most of its time hanging out close to the bottom, digging, or exploring caves and crevices? If so I'd call it female. If it spends more time swimming in open water (especially in any kind of pattern), and nipping at or chasing passer-bys, it's probably male. Of course males and females will do both to a certain extent, so you have to watch over a long enough period of time to tell which behavior is prevalent.
Now as for adding a few more...
Let's just say it would be tricky. My opinion is that you will not have good chances due to the size of the one you have now (We'll call it female untill you know different). It is still *possible* to get a mate for her, if the new additions are of similar size. I do NOT recommend trying this though, because the answer to your main question is YES, unless you have an extremely large tank! Knowing their aggression as I do, it would not be surprising to me to find a large male N. pulcher (or brichardi even moreso) claiming 9sq feet of territory. That would be the entire floor of a 125g tank. If no newly added males accept her, they will probably all fight till death untill only one is left, unless you remove them. If one does accept her, the newly formed pair will kill all the rest. Unless you remove them.
You'd be much better off starting with a new group of 5 to 7 fish, if you're interested in breeding pulchers for the sake of the species and hobby. Even as sub-adults, once a pair forms, that pair will drive the rest away, or kill them if the tank's not big enough. (Unless you remove them.
) My male was given to me by a local breeder in a group of 6 fish. He killed all the rest, all at night, over the next two weeks or so. A month I got another group of 6 from the same breeder, who were from the next batch of fry after the batch the first 6 came from. This time, my male found a female he liked. Great, I thought. Then he *and* the female went about killing the rest.
If you just want to breed the pulcher you have now, your work's cut out for you, especially if it's in a community tank. If you have another tank that's cycled but has no livestock, you can increase your chances by moving your female over to it and adding the new fish at the same time. There will still violent aggression, but I think you would be more likely to get a pair.
Whatever you decide to do, you have my best wishes. Good luck!